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Making Leaf Springs Work

Leaf springs are some of the oldest mechanical devices conceived by man; dating back to medieval times. They are still being used to this day because they work. They support the vehicle’s weight, they conform to the terrain, and they locate the axle. They also distribute the load on a large portion of the frame. Leaf springs are far from an outdated design; they are found on the latest Chevrolet Corvette suspension. The Corvette uses a high-tech composite, transverse mono-leaf, but it’s still a leaf spring.

Unfortunately, leaf springs have gotten a bad rap. When improperly designed, they can be harsh. Some spring suppliers, including the manufacturers, use thicker and fewer leaves to reduce cost. They also design them to be one size fits all. To ensure you get the advertised height, they make them towards the stiff end of the scale. However, a properly designed leaf spring can hold your truck up and give a comfortable ride.

Custom spring makers blueprint the leaf packs, designing them to match your vehicle’s weight and intended use. They are carefully hand crafted and use additional leaves to give you a nice progressive spring rate. They use multiple leaves of different widths, lengths and thicknesses to be supple at ride height for a smooth ride but still have the beef to take on rough terrain. One such spring maker is Atlas Spring in City of Industry, California. They built a custom set of springs for a Ford F-350 that regularly hauls a camper into remote areas. The factory springs were built to simply haul a load; this truck needs to haul something else. If they can make this 10,000-pound rig comfortable and controlled in the dirt, they can make your rig do the same.

Step By Step

1. Atlas Spring owner Juan F. Gutierrez uses vehicle information, an extensive database, and years of spring-building experience to blueprint a set of custom springs.

2. North American-made 5160 heat-treated alloy steel blanks made to Atlas Spring Specs are used to construct each spring pack.

3. Blanks are selected that match the specs called out on the blueprint.

4. The blanks are numbered and carefully laid out before each is cut to length.

5. The leaves are then cut, drilled, and deburred by hand.

6. The main leaves are heated in a 250,000 BTU forging furnace for five minutes to roll the eyes on each end.

7. The ends are rolled using specialized tooling to ensure a consistent loop and the perfect diameter for the bushing.

8. Note the perfect symmetry between each spring eye.

9. After heating and then cooling, the arch may change slightly. The specified arch is achieved with some fine-tuning on a hydraulic press.

10. The bushings are pressed in with this cool 100-ton press. Yes, the flames make it faster.

11. Special inserts on each diamond-tipped end reduce friction between leaves. They allow the springs to slide quietly and easily, giving you a smooth ride.

12. More specialized equipment: This press precisely forms the spring clips around the leaf.

13. Nearly complete, the spring packs get a center pin to hold them together and locate them on the rear axle.

14. After the spring packs are painted, assembled, and stickered with the Atlas logo and a proud-to-be-made-in-America decal, spring rate is verified for accuracy.

15. This F-350 also got a shackle reversal kit from Sky’s Off Road Design. The kit moves the shackle mounting location from the front of the spring to the rear, which allows the springs to move up and back when hitting an obstacle. The wheels and tires now follow the ground instead of bouncing over it.

16. The factory front springs were made from two thick leaves that were very stiff. The Atlas Spring pack has seven springs that provide a smooth progressive spring rate. The difference is amazing!